Storing soups and stews is about achieving two goals: primarily, to make sure the food stays safe and free from microorganisms that can cause illness, and also maintaining quality.
There are three main techniques you can use, depending on how long you want to keep the soup, as well as what ingredients the soup or stew contains.
Refrigerating Soups and Stews
The simplest way to store soups and stews (if you're planning to use them within a few days) is in the fridge. Refrigerating soups and stews is mostly a matter of transferring it to some sort of container with a tight-fitting lid and getting it into the fridge within two hours. It's best to let it cool fully first, but don't worry too much if the soup is still warm—modern refrigerators, set to 40 F or colder, will rapidly bring it down to a safe temperature.
You can, if you have room, even refrigerate the whole pot with the soup in it. But regardless of what you store it in, soups and stews will keep in the refrigerator for around three days. And fortunately, with simple refrigeration, you don't have to worry about certain ingredients in the soups causing problems, as you do with the next two storage methods.
Freezing Soups and Stews
Freezing soups and stews will significantly extend their shelf life as compared with storing them in the fridge. Soups and stews will comfortably last up to three months in the freezer, assuming they are stored properly.
The main issue with freezing soups and stews is quality as it relates to the specific ingredients in the soups. Ingredients like pasta and noodles, milk, cream, cheese and other dairy products, as well as rice and potatoes, are all problematic in the freezer for various reasons.
Starchy ingredients like pasta, rice and potatoes absorb too much of the soup's liquid, turning them mushy. Dairy products can separate. This is not to say that you can't safely freeze soups and stews that contain these types of ingredients, but just know that they won't fare as well in the freezer as soups without them.
And in large part this comes down to the question of whether you're preparing soup specifically for the freezer, in which case you can leave out those ingredients and add them later prior to serving, or whether you're looking to freeze leftovers, in which case, you just have to go with what you have. In general, the less time things spend in the freezer, the better they'll be. So with soups that contain these problem ingredients, think in terms of using them within weeks rather than months.
Pint or quart-sized containers will work fine, as long as they're made of freezer-safe material. Tempered glass (or other glass specifically labeled as safe for the freezer) is acceptable, but even these products can crack if subjected to rapid temperature changes, or if they're packed too full.
One thing you don't have to worry about with soups and stews is freezer burn. Ice crystals can form on the tops of frozen soups and stews, but actual freezer burn, where the surface of a frozen item becomes dry and discolored through loss of moisture, isn't an issue with foods that are mostly liquid. With ice crystals, you can scrape them off or not, as it's just the moisture from the soup being drawn to the surface. It's fine to melt them back into the soup.
To really avoid ice crystal formation, freeze your soups and stews in freezer bags with excess air pressed out (filing them in a clear organizer will make it easy to sort your soups!), or in freezer containers with a piece of plastic wrap draped across the surface of the soup.
Do try to cool your soup or stew to room temperature before transferring it to the freezer. Food that is is slightly warm is more prone to forming ice crystals. But in any event, don't let it sit at room temperature for more than two hours.
Canning Soups and Stews
Another method for storing soups and stews is to can them. The main advantage to canning soups and stews is that they will keep for up to a year, as opposed to three months in the freezer. But along with that longer shelf life comes the necessity to follow strict procedures and stick to tested recipes.
The most important factor is that soups and stews are low-acid foods and thus they need to be canned using a pressure canner, as opposed to the hot water bath canning method that is used for canning acidic foods like fruits.
Canning soups containing pasta, rice, flour, dairy, or thickeners like cornstarch is not safe, as they can interfere with the achieving of the proper temperature for killing potentially harmful bacteria. These ingredients can be added prior to serving.
Likewise, certain ingredients, such as beans, lentils and split peas need to be cooked, not dry. If you follow the recipes and guidelines from a trusted site, canned soups and stews can be stored in a cool, dry, dark place for up to a year. Also, the USDA advises that it's not safe to freeze puréed soups. (But you can always purée it before serving.)